Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 191824
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
1224 PM CST Sun Feb 19 2017

.UPDATE...
Issued at 1218 PM CST Sun Feb 19 2017

Made a few adjustments to temperatures, mainly to lower a bit
across the north. Also extended the mention of fog through the
afternoon across the northwest, and then expanding into the north
central this evening. Updated text products will be sent shortly.


UPDATE Issued at 936 AM CST Sun Feb 19 2017

Main forecast issue today will be stratus/fog and temperatures.

Surface low pressure over southeast Montana will move east into
the western Dakotas today, with a warm front extending eastward
along the ND/SD border. Over western and central ND this morning
east to southeast convergent flow is producing stratus/fog over
west central into northwest ND. We extended fog through the
morning for this area, and into the afternoon over the far
northwest. Elsewhere broad southwest upper flow is bringing
substantial mid and high level clouds across the forecast area so
bumped up sky cover as well this morning. Strong warm advection
is expected to shift into southwest and central ND today, but with
current cloud/fog trend, the warm temperatures appear to be in
jeopardy, especially across the north. Have lowered temperatures
a bit in the north and central. For now will leave highs alone in
the south and will take another look around midday.

UPDATE Issued at 602 AM CST Sun Feb 19 2017

Latest surface observations continue to show patchy fog across
the southwest which is projected to shift into northwest and north
central ND through the morning. Thus have added this into the
forecast. Also adjusted POPS/Weather based on the latest
HRRR/RAP13/NAMNest which advertises isolated to scattered showers
in the James River Valley, and light freezing rain north central
in the morning. Although no ground truth to any precipitation as
of yet, the current radar trends suggest the above model blend is
on track.

&&

.SHORT TERM...(Today and tonight)
Issued at 311 AM CST Sun Feb 19 2017

Low level baroclinic zone per NAM/GFS/RAP13 is currently shifting
into north central North Dakota this morning. Main concern for
this morning is light freezing rain developing across the north
central. Although nothing has developed as of now, that could
change as a series of weak shortwaves slide into southwest North
Dakota this morning inducing weak synoptic scale ascent atop the
baroclinic zone. The latest gridded forecast along with the
HRRR/GFS and to some extent the ECMWF, continue with this trend
and will follow for the morning forecast. Farther south, patchy
fog has developed across portions of the southwest and south
central. While the HRRR continues to overdo the areal coverage of
fog, it does shift the fog potential into the north through mid
morning.

Southwest flow aloft continues through tonight with a couple of
minor shortwaves scooting through today, and a much stronger
shortwave trough slated for tonight. Although ascent is also
noted in the James River Valley today, there is some indication
that an isolated shower could develop. Radar reflectivitys have
been increasing slightly here early this morning, and with
continued weak ascent, will mention isolated showers through early
afternoon in the James River Valley. Otherwise warm air advection
continues through the afternoon with 850mb temperatures of +12C
to +14C briefly becoming established across south central North
Dakota. Some sunshine across the south this afternoon should allow
for highs to reach into the 50s, especially southwest and southeast.
Blended previous forecast highs with the warmer MAV guidance for
today.

For tonight, as mentioned above a stronger shortwave trough now
over southeast Arizona will lift northeast. A cold front associated
with it will shift through western and central North Dakota, with
increasing chances for precipitation (mainly rain toward 06z and
onward). However, light freezing rain is again a possibility across
the north central tonight into Monday morning. Will continue to
mention this in the HWO for now and allow the day/evening shift
decide if ongoing trends warrant a possible special weather statement
as we get closer to the event.

.LONG TERM...(Monday through Saturday)
Issued at 311 AM CST Sun Feb 19 2017

Breezy Monday as the surface cold front and upper shortwave trough
sweep through. Still enough low level cape and adequate shear for
a slight chance of thunderstorm mention in the far southern James
River Valley Monday morning. The bulk of the precipitation will
occur in the morning, tapering off quickly from west to east by
early afternoon as clouds decrease and sunshine returns.

Another system slides through beginning Tuesday afternoon through
Wednesday afternoon, mainly affecting northern North Dakota.
Colder air filtering in behind this system late Wednesday into
Thursday will be felt for the rest of the extended period. Rain is
forecast to change over to snow across the north Tuesday night.
Potential for up to one inch in the far north. Across the south,
expect mild temperatures Tuesday with highs in the 50s, and
possible lower 60s southwest. Cooler Wednesday with highs in the
lower 30s north to mid 40s south. Another system slated for
Thursday through Friday continues to trend snow chances south of
Interstate 94. Because of this more southerly track, colder air
via a northerly flow will encompass all of western and central
North Dakota. Expect highs only in the 20s Friday and Saturday.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1218 PM CST Sun Feb 19 2017

An area of low stratus is currently over portions of western and
north central ND. This area of low stratus will remain mainly over
the northwest and far north central this afternoon and then expand
in areal coverage tonight. Late tonight into Monday morning, an
upper level system will swing through the area bringing a period
of rain showers followed by clearing skies as winds shift west.
There is a small threat of mixed precipitation, including freezing
rain. Confidence too low at this time to mention in the TAFs.
Clearing expected to be moving through KJMS around 18Z Monday.


&&

.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE...TWH
SHORT TERM...KS
LONG TERM...KS
AVIATION...TWH



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